Mount structure of a light emitting element array in electronic photographic apparatus

ABSTRACT

A light emitting element array in an electronic photographing apparatus, in which a photoconductor drum is exposed to a light from a light emitting array having a plurality of light emitting diodes to form a latent image on the drum, and a high quality, stable light image can be deposited on the photoconductor drum from a light emitting array, even after extended use. The constitution is such that a fixed bracket 31 is fixedly mounted on the electronic photographing apparatus, a rotatable bracket 33 is rotatably mounted on the fixed bracket and fixedly secured to the light emitting element array 2, a bias means 37 urges the light emitting element array 2 against the outer surface of the photoconductor drum 1, a space keeping means 38 is pushed by the bias means against the outer surface of the photoconductor drum so as to maintain a constant distance between the light emitting element array and the outer surface of the photoconductor drum 1.

TECHNICAL FIELD

This invention relates to a mount structure of a light emitting elementarray in an electronic photographing apparatus, in which aphotoconductor drum is exposed to a light from a light emitting arrayhaving a plurality of light emitting diodes to form a latent image onthe drum.

In such a mount structure of a light emitting element array in anelectronic photographing apparatus, a beam emitted from a light emittingelement is focused on a photoconductor drum by a lens so that a beamradiated from one light emitting element forms one dot of an image.Therefore, a precise distance between the light emitting array and thephotoconductor drum must be maintained.

BACKGROUND ART

FIG. 5 shows a mount structure of a light emitting element array in anelectronic photographing apparatus known in the prior art (FIG. 5(A)being a front view and FIG. 5(B) being a side view). A plurality oflight emitting diodes (LED) are arranged on a LED array 91 that isrigidly mounted on leaf springs 92. The bearings (spacing means) 94rotatably mounted on the LED array 91 are urged to the photoconductordrum 95, so that the distance between the LED array 91 and outerperiphery of the photoconductor drum (information recording media) 95remains constant.

However, due to the rotating photoconductor drum 95, the leaf springs 92vibrate in the direction A, so that the bearings 94 do not stablycontact the surface of the photoconductor drum 95. Therefore, the leafsprings 92 are pushed from the back thereof by means of rubber dampers97 mounted on the fixed bracket 96 so as to restrict the vibration ofthe leaf springs 92 and prevent a rough printing.

In the mount structure of a light emitting element array in anelectronic photographing apparatus known in the prior art as mentionedabove, the bearings 94 are strongly urged to the surface of thephotoconductor drum 95 by a damping force of the rubber dampers inaddition to a spring force of the leaf springs 92 and, therefore, thesurface of the photoconductor drum 95 becomes worn after extended use,so that the distance between the LED array 91 and the periphery of thephotoconductor drum 95 is reduced. Thus, focusing on the photoconductordrum 95 for one dot will be out of order and image quality willdeteriorate.

Also, the leaf spring 92, particularly, the central portion 92a thereofwhich is not pushed by the rubber damper 97 vibrates or is twisted, sothat the image deposited on the photoconductor drum 95 will deteriorateor will produce jitters (disorder of dots) and image quality is reduced.

DISCLOSURE OF INVENTION

An object of the present invention is to provide a mount structure of alight emitting element array in an electronic photographing apparatus,in which a high quality stable light image can be deposited on thephotoconductor drum from a light emitting array, even after extendeduse.

According to the present invention, there is provided a mount structureof a light emitting element array in an electronic photographingapparatus, comprising a cylindrical photoconductor drum rotatably drivenaround an axis, a light emitting element array having a plurality oflight emitting elements arranged parallel to the axis of thephotoconductor drum and opposite to an outer surface thereof,characterized by a fixed rigid bracket fixedly mounted on the electronicphotographing apparatus; a rotatable rigid bracket rotatably mounted onthe fixed bracket and fixedly secured to the light emitting elementarray; a bias means for urging the light emitting element array againstthe outer surface of the photoconductor drum; a space keeping means thatis pushed by the bias means against the outer surface of thephotoconductor drum so as to maintain a constant distance between thelight emitting element array and the outer surface of the photoconductordrum.

It is advantageous for the rotatable bracket to be rotatably mounted onthe fixed bracket by a pair of bearings arranged a certain intervalapart in such a manner that, at one of the bearings, the rotatablebracket is supported on said fixed bracket so as to be movable andparallel to the beam radiated from the light emitting element array.

In addition, both the fixed bracket and the rotatable bracket may bemade of rigid metal plates. The space keeping means comprises bearingsrotatably mounted on the light emitting element array in such a mannerthat said bearings are forced against the outer surface of thephotoconductor drum and rotated by the rotation of the photoconductordrum.

Thus, the light emitting element array is supported by the fixed bracketand the movable bracket made of rigid bodies and urged toward the outersurface of the photoconductor drum with the rotatable bracket by thebias means. The distance between the light emitting element array andthe other surface of the photoconductor drum can remain constant by thespace keeping means.

In another aspect of the present invention, there is provided a mountstructure of a light emitting element array in an electronicphotographing apparatus, comprising a fixed bracket and a rotatablebracket rotatably mounted on the fixed bracket at the respective endsthereof in the axial direction and providing a light emitting elementarray for forming an electrostatic latent image; said array having aplurality of light emitting elements along the axial direction of theinformation recording media (photoconductor drum) rotatably driven aboutan axis thereof and a pair of gap keeping means for maintaining a gapwith the photoconductor drum; a first bias means, provided between thefixed bracket and the rotatable bracket, for urging the light emittingelement array so that both space keeping means are in contact with thephotoconductor drum; one of the respective axial ends at which saidrotatable bracket rotatably connected to said fixed bracket is onlyrotatably supported to said fixed bracket, and the other end beingconnected to the same rotatably and movably toward and away from thephotoconductor drum; and second bias means integrally mounted on saidfixed bracket for urging said other end of the rotatable bracket towardsaid photoconductor drum.

Although a portion of the elongated hole of the rotatable bracket issubjected to micro-vibration, the portion is urged toward theinformation recording media by the second bias means integrally mountedon the movable bracket, thereby restricting such a vibration andpreventing a printing disorder.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side cross-sectional view of a first embodiment;

FIG. 2 is a side schematic view of a printer according to the presentinvention;

FIG. 3 is a perspective view of the first embodiment;

FIG. 4 is a side view of a second embodiment;

FIG. 5 shows a prior art, particularly, (A) is a front view and (B) is aside view.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments will now be described with reference to the drawings.

FIG. 2 shows a printer of the present invention. In the drawing, thereference numeral 1 denotes a photoconductor drum rotated in thedirection B about an axis and has a cylindrical outer surfaceelectrified by a pre-electrification unit, not illustrated.

The reference numeral 2 denotes a light emitting diode array in which aplurality of light emitting diodes are arranged parallel to the axialdirection of the photoconductor drum 1. One image beam of one dot fromone light emitting diode is radiated to the outer surface of thephotoconductor drum and a latent image is formed on the outer surface ofthe photoconductor drum 1.

The reference numeral 4 denotes a developing unit for developing thelatent image on the photoconductor drum 1 with a toner; 5, a transferunit for transferring the toner image on the photoconductor drum 1 to arecording sheet; and 6, a cleaner for cleaning the toner remaining onthe outer surface of the photoconductor drum 1. The recording sheet 100is fed by a sheet feeding roller 7 to a passage in a printer and thetoner image is fixed onto the recording sheet 100 by a fixing unit. Thefixed recording sheet 100 is then discharged by a discharge roller 106to a stacker 107, and after the transfer operation, the surface of thephotoconductor drum 1 is cleaned by the cleaner 6.

FIG. 3 is a perspective view of a supporting section for supporting thelight emitting diode array and FIG. 1 is a side sectional view thereof.

The reference numeral 21 denotes a light emitting diode (LED); and 22denotes a drive circuit thereof, which are both mounted on a printedboard 23. A beam emitted from the light emitting diode 21 is focused bya focusing lens 24 on the outer surface of the photoconductor drum 1.The light path of this beam is directed to the center axis 0 of thephotoconductor drum 1.

The reference numeral 31 denotes a fixing bracket made of a rigid metalplate fixed on the printer by screws. The shafts 32 are projected fromthe right and left ends of the bracket. A rotatable bracket 33 also madeof a rigid metal plate is rotatably supported on the shafts 32. One ofthe bearing holes 34 and 35 engaged with the shafts 32 has a circularsection engaged with the shaft 32 and the other bearing hole 35 is anelongated hole extending in the same direction as the light path of thebeam emitted from the light emitting diode 21.

The reference numeral 37 is a torsion spring for urging the rotatablebracket 33 around the shaft 32 and, thus, the light emitting diode array2 is urged toward the outer surface of the photoconductor drum 1. Saidtorsion springs each including a spiral portion 37a which is spiralledaround shaft 32, as shown in FIG. 3.

The respective bearings 38 are rotatably mounted at the left and rightends of the light emitting diode array 2, so that the head portionsthereof are projected toward the photoconductor drum 1. Therefore, thebearings 38 are always urged to the outer surface of the photoconductordrum 1 by the bias force of the torsion springs 37 and thus the distancebetween the light emitting diode array 2 and the photoconductor drum 1always remains constant.

Due to the position or mount errors of various members, such as, thefixed bracket 31 and the photoconductor drum 1, the light emitting diodearray 2 may not be parallel to the outer surface of the photoconductordrum 1 and, therefore, one of the pair of bearings 38 may not contactthe photoconductor drum 1.

However, since one of the bearing holes is an elongated hole parallel tothe light path of the beam as mentioned above, the shaft 32 at the sideof the elongated bearing hole 35 is freely movable in the directionparallel to the light path, toward or away from the outer surface of thephotoconductor drum 1.

Therefore, if the bracket 31 is fixed so that the position at thecircular bearing hole 34 is set at an appropriate position, the left andright bearings 38 are both urged to the outer surface of thephotoconductor drum 1 and thus the light emitting diode array 1 isautomatically set in an appropriate position so as to be parallel to theouter surface of the photoconductor drum 1.

According to the first embodiment of a mount structure of a lightemitting element array in an electronic photographing apparatus, therotatable bracket for mounting the light emitting element array and thefixed bracket for supporting the same are both rigid bodies and mutuallyand rotatably connected by means of a bias means. Therefore, vibrationor torsion can be prevented as a whole and a high quality light imagecan be produced on the photoconductor drum.

In addition, it is no longer necessary to provide a rubber damper or thelike to absorb the vibration, and therefore the space keeping means,such as bearings, can be forced to the surface of the photoconductordrum by a small force. Therefore, wear of the photoconductor drum isvery small for extended use and the distance between the light emittingelement and the outer surface of the photoconductor drum is minimal, andthus a good focus, less jitter and stable exposure can be maintained.

Also, one of the supporting means for supporting the light emittingelement array by its respective ends is movable and parallel to thelight path of the beam, and therefore the light emitting element arrayis automatically parallel to the outer surface of the photoconductordrum. Thus, since a parallel adjustment is no longer necessary at thetime of assembling the same, a mount can very easily be effected and theapparatus can be assembled beforehand as an unit.

FIG. 4 is a side view of a second embodiment of a mount structure of anoptical head in an electronic photographing apparatus according to thepresent invention. In the drawing, the reference numeral 31 denotes afixed bracket, which is the same as the fixed bracket 12 in FIG. 1,except that it integrally provides a bracket pushing spring 42 (a secondurging means). The other structural members are indicated by the samereference numerals as FIG. 1.

The bracket pushing spring 42 urges the portion of the ring hole of therotatable bracket 33 in a direction toward the photoconductor drum 1,i.e., in the direction parallel to the light path. Therefore, themicro-vibration of the rotatable bracket 33 at the portion of theelongated hole 35 can be restricted and the respective gap bearings 38can be forced to the photoconductor drum 1, so that the distance betweenthe photoconductor drum 1 and the optical head (LED array) 2 remainconstant.

As a result, the problem in the prior art, i.e., a print disarray can beprevented. The bracket pushing spring 42 can be small enough to restrictmicro-vibration, so that it does not affect the force of the gapbearings 38 for pushing the photoconductor drum 1.

As mentioned above, the respective gap bearings 38 of the optical head(LED array) are stably pushed to the photoconductor drum 1 at therespective ends thereof by means of the bracket pushing springs 42, sothat the distance between the photoconductor drum 1 and the optical head2 remains constant. Therefore, the beam from the optical head 2 isfocused stably on the surface of the photoconductor drum 1 so as toprevent a print disorder.

According to the second embodiment as mentioned above, the respectivegap bearings of the optical head (LED array) are in constant and stablecontact with the surface of the photoconductor drum 1 at the respectiveends thereof.

Industrial Applicability

It should be understood by those skilled in the art that the presentinvention can be applied to various kinds of electronic photographingapparatuses, in which light emitting element arrays each having aplurality of light emitting elements arranged parallel to the axis ofthe photoconductor drum are arranged with a certain interval along theouter surface of the photoconductor drum.

What is claimed is:
 1. A mount structure of a light emitting elementarray in an electronic photographic apparatus, comprising aphotoconductor drum (1) rotatably driven around an axis, a lightemitting element array (2) having a plurality of light emitting elements(21) arranged parallel to the axis of the photoconductor drum (1) andopposite to an outer surface thereof, characterized bya fixed bracket(31) fixedly mounted on the electronic photographing apparatus; arotatable bracket (33) rotatably mounted on the fixed bracket (31) andfixedly secured to the light emitting element array (2); a bias means(37) for urging the light emitting element array (2) against the outersurface of the photoconductor drum (1); a space keeping means beingpushed by the bias means (37) against the outer surface of thephotoconductor drum (1) so as to maintain a constant distance betweenthe light emitting element array (2) and the outer surface of thephotoconductor drum (1); wherein the rotatable bracket (33) is rotatablymounted on the fixed bracket (31) by a pair of bearings (34, 35)arranged a certain interval apart and parallel to the axis of thephotoconductor drum (1); the rotatable bracket (33) is supported on saidfixed bracket (31) so as to be movable toward or away from thephotoconductor drum (1) at one of the bearings (35); wherein said one ofthe bearings (35) comprises an elongated hole (35) formed by either oneof the fixed bracket (31) and the rotatable bracket (33) and a shaft(32) provided on the other bracket and engaged with the elongated hole(35); and wherein the bias means (37) for urging the light emittingelement array (2) against the outer surface of the photoconductor drum(1) comprises a pair of torsion springs arranged in the vicinity of saidpair of bearings (34, 35), respectively.
 2. A mount structure of a lightemitting element array in an electronic photographing apparatus as setforth in claim 1, wherein the fixed bracket (31) and the rotatablebracket (33) are both made of rigid metal plates.
 3. A mount structureof a light emitting element array in an electronic photographingapparatus as set forth in claim 1, wherein said space keeping meanscomprises bearings rotatably mounted on the light emitting element array(2) at the respective ends thereof in such a manner that said bearingsare pushed against the outer surface of the photoconductor drum (1) androtated by the rotation of the photoconductor drum (1).
 4. A mountstructure of a light emitting element array in an electronicphotographing apparatus as set forth in claim 1, wherein said pair ofsprings each have a spiral portion which is spiralled around said shaft(32).
 5. A mount structure of a light emitting element array in anelectronic photographing apparatus, comprising a fixed bracket (31) anda rotatable bracket (33) rotatably mounted on the fixed bracket (31) atthe respective ends thereof in the axial direction and provided with alight emitting element array (2) for forming an electrostatic latentimage; said array having a plurality of light emitting elements (21)along the axial direction of the photoconductor drum (1) rotatablydriven about an axis thereof and a pair of gap keeping means (38) formaintaining a gap with the photoconductor drum (1);a first bias meansprovided between the fixed bracket (31) and the rotatable bracket (33),for urging the light emitting element array (2) so that both gap keepingmeans (38) are in contact with the photoconductor drum (1); one of therespective axial ends at which said rotatable bracket (33) rotatablyconnected to said fixed bracket (31) being only rotatably supported tosaid fixed bracket (31), and the other end being connected to the samerotatably and movably toward and away from the photoconductor drum (1);and second bias means integrally mounted on said fixed bracket (31) forurging said other end of the rotatable bracket (33) toward saidphotoconductor drum (1).
 6. A mount structure of a light emittingelement array in an electronic photographing apparatus as set forth inclaim 5, wherein one end of the rotatable bracket (33) is provided witha round hole (34) that is engaged with one end of a shaft (32) mountedon the fixed bracket (31), and the outer end is provided with anelongated hole (35) extending in a direction toward or away from thephotoconductor drum (1) and engaged with the other end of said shaft(32).
 7. A mount structure of a light emitting element array in anelectronic photographing apparatus as set forth in claim 6, wherein saidfirst bias means (37) comprises a pair of torsion springs mounted onsaid shaft (32) near rotatable connecting positions at the respectiveends of the fixed bracket.